1. Field of the Invention
The present invention relates to a method and a device for generating energy which can be used, for example, for carrying out operations with pressurized air during the rolling of a tyre fitted on a rim, and, in particular, for supplying compressed air which can be used to obtain the desired pressure level within the tyre during the running of a motor vehicle.
2. Description of the Related Art
During the operation of a motor vehicle, a knowledge of the value of the tyre pressure is an extremely important factor for the continuous control of the tyres and for ensuring safe travel of the motor vehicle. This is because keeping the pressure at the specified value enables the best possible performance to be obtained from the tyre in terms of wear, rolling resistance, roadholding, braking etc., and affects the safety of the driving of the motor vehicle.
There are known devices designed to generate pressurized air to be sent into a tyre of a motor vehicle during running.
U.S. Pat. No. 5,409,049 describes an apparatus for pressurizing a tyre fitted on a wheel. The apparatus includes a displacement-type air pump consisting of a free and oscillating piston body provided with a reciprocating linear motion by the action of forces produced by the rotary motion of the wheel. The apparatus also includes support means for supporting the piston without friction during its oscillation within the pump, in order to generate pressurized air. It also includes suitable mounting means for fixing the pump to the wheel on which a tyre is fitted in such a way that the path of reciprocating motion of the piston is out of alignment with the centre and forms a tangent to a path of rotation of the wheel. Additionally, it includes suitable connection means for introducing into the tyre the pressurized air generated by the pump.
U.S. Pat. No. 5,667,606 describes an apparatus for pressurizing a tyre fitted on a wheel. The apparatus includes a displacement-type air pump, consisting of a combination of a cylinder and a spring-loaded piston. The pump has a casing suitable for being fixed axially to the wheel. The apparatus also includes a connecting conduit for pressurized air, suitable for introducing into the tyre the pressurized air generated by the pump. The apparatus also includes a cam and a cam follower mounted in the casing. The cam follower engages with the cam to create relative movements between them, caused by the cam, and is connected to the pump in order to drive it. A pendulum is mounted in the casing so that it rotates freely with respect to it. The pendulum is connected to one of the said cam and cam follower to keep this component essentially stationary with respect to the other, while the other of these components is fixed to the casing so that it rotates with it and provides the movement which drives the pump. The cylinder and piston combination has an axis of reciprocating motion of the piston in the cylinder which is essentially aligned with the axis of rotation of the wheel.
The apparatus of U.S. Pat. No. 5,409,049 makes use of the energy potentially contained and/or generated by a wheel of a motor vehicle when it is rotating. In particular, the apparatus makes use of the variation of the gravitational energy (weight) which occurs when use is made of a body which has an intrinsic weight applied to the wheel and which is free to move with respect to the rotating wheel.
The apparatus of U.S. Pat. No. 5,667,606 uses a cam, a cam follower and a pendulum to convert the rotary motion of the wheel into reciprocating motion of the pump piston.
These known apparatus are complicated, delicate and expensive. Moreover, they are positioned on the outside of the wheel. They are therefore subject to stresses and deformations which can cause frequent failure.
Another disadvantage lies in the fact that the application to the wheel of a body (a free oscillating piston or pendulum) having a specific intrinsic weight necessitates a precise balancing of not only the tyre but also the wheel, in order to achieve an acceptable uniformity of operation.
The objects of the present invention are a device and method for generating energy which can be used, for example, in order to carry out operations with pressurized air suitable for pressurizing a tyre during the running of a motor vehicle, which avoids the disadvantages of the known apparatuses.